From 800b9e3e375ee74fe432da5f932f0d49a63c188a Mon Sep 17 00:00:00 2001
From: Zhongyang Wu <zhongyang.wu@outlook.com>
Date: Thu, 1 Jun 2023 09:59:09 -0700
Subject: [PATCH] fix: allow span id to be less than 16 characters in jaeger
 propagator (#1084)

---
 opentelemetry-jaeger/CHANGELOG.md |  4 ++++
 opentelemetry-jaeger/src/lib.rs   | 27 +++++++++++++++++++++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/opentelemetry-jaeger/CHANGELOG.md b/opentelemetry-jaeger/CHANGELOG.md
index 6628532400..6b75c144ec 100644
--- a/opentelemetry-jaeger/CHANGELOG.md
+++ b/opentelemetry-jaeger/CHANGELOG.md
@@ -1,4 +1,8 @@
 # Changelog
+## Main
+### Fixed
+- allow span id to be less than 16 characters in propagator [#1084](https://github.com/open-telemetry/opentelemetry-rust/pull/1084)
+
 ## v0.18.0
 
 ### Added
diff --git a/opentelemetry-jaeger/src/lib.rs b/opentelemetry-jaeger/src/lib.rs
index e568982e0b..cf912caf15 100644
--- a/opentelemetry-jaeger/src/lib.rs
+++ b/opentelemetry-jaeger/src/lib.rs
@@ -484,11 +484,17 @@ mod propagator {
 
         /// Extract span id from the header.
         fn extract_span_id(&self, span_id: &str) -> Result<SpanId, ()> {
-            if span_id.len() != 16 {
-                return Err(());
+            match span_id.len() {
+                // exact 16
+                16 => SpanId::from_hex(span_id).map_err(|_| ()),
+                // more than 16 is invalid
+                17.. => Err(()),
+                // less than 16 will result padding on left
+                _ => {
+                    let padded = format!("{span_id:0>16}");
+                    SpanId::from_hex(&padded).map_err(|_| ())
+                }
             }
-
-            SpanId::from_hex(span_id).map_err(|_| ())
         }
 
         /// Extract flag from the header
@@ -589,6 +595,7 @@ mod propagator {
         const SHORT_TRACE_ID_STR: &str = "4d0000000000000016";
         const TRACE_ID: u128 = 0x0000_0000_0000_004d_0000_0000_0000_0016;
         const SPAN_ID_STR: &str = "0000000000017c29";
+        const SHORT_SPAN_ID_STR: &str = "17c29";
         const SPAN_ID: u64 = 0x0000_0000_0001_7c29;
 
         fn get_extract_data() -> Vec<(&'static str, &'static str, u8, SpanContext)> {
@@ -617,6 +624,18 @@ mod propagator {
                         TraceState::default(),
                     ),
                 ),
+                (
+                    SHORT_TRACE_ID_STR,
+                    SHORT_SPAN_ID_STR,
+                    1,
+                    SpanContext::new(
+                        TraceId::from_u128(TRACE_ID),
+                        SpanId::from_u64(SPAN_ID),
+                        TraceFlags::SAMPLED,
+                        true,
+                        TraceState::default(),
+                    ),
+                ),
                 (
                     LONG_TRACE_ID_STR,
                     SPAN_ID_STR,